The invention relates to a casing made of molded plastic material, comprising :
a rigid hollow body having a back panel and a side wall of revolution equipped with an end part located opposite the back panel, PA1 a closing cover coming into engagement against the end part, PA1 a male first thread arranged along the external surface of the side wall of the body, PA1 and a fixing ring having a female third thread designed to be screwed onto the male first thread to ensure that the cover is held stably against the end part.
Domestic lighting lamps generally have a cylindrical end part, and the transparent window is fixed onto the end part by means of a ring with internal threading. The transparent window or screen can be a separate part or be integrated into the ring, which is of cylindrical shape. This type of lighting lamp comprises a single electric bulb supported by a holder fixed to a parabolic reflector, located coaxially with respect to the casing.
Some lighting lamps for industry comprise a double focusing system using two electrical bulbs and two reflectors arranged side by side. Incorporating this system in a cylindrical casing means that large dimensions are required, which is incompatible for the use of headsets, which are worn on the user's head.
Reducing the dimensions of the casing requires a modification of the rigid body, for example by replacing the circular cross-section of the end part and associated cover by a non-circular shape. The use of a screw ring with a rigid structure is however impossible to provide closing of the casing.
A first object of the invention consists in achieving a casing of non-circular cross-section sealed by a tightening ring.
A second object of the invention consists in achieving a sealing system in a non-circular casing.